Is Heat Recovery Always Worthwhile? Balancing Energy Savings with Hazardous Material Cleaning and Maintenance
Mary On, Integral Group
Many laboratories recover waste heat from fume hood exhaust using runaround coils; however, it requires special maintenance procedure as the filters and coils in the exhaust air stream are contaminated by chemicals and are hazardous. The maintenance staff often needs to consult with the Health and Safety department prior to starting work and will need to wear the appropriate PPE. The dirty filters will also need to be handled and disposed of as hazardous waste. This special maintenance procedure is lengthy and expensive over the lifetime of the building. Given the complicated and costly maintenance required, the design team should carefully weigh the pros and cons of incorporating fume hood exhaust heat recovery, and balance the amount of energy that could potentially be saved with the operating cost. It is possible for a lab to achieve high energy performance without fume hood heat exhaust. This presentation will look at how two university lab buildings achieve low energy use intensity (EUI) without the use of fume hood exhaust heat recovery.
Completed in 2017, the Quantum Matter Institute (QMI) at the University of British Columbia is a 5 storey, 51,000 sf building with the floor area shared equally by offices and physics labs. The lab building only has 13 fume hoods, in which the fume hood exhaust volume accounts for less than 20% of the total building exhaust air. The project design includes energy saving strategies such as general exhaust heat recovery, re-using air from non-lab area to reduce outdoor air intake, water source heat pumps to use rejected heat to provide building heating, and heat recovery of clean general building exhaust air. The modeled energy use is 110 kBtu/sf/year even without fume hood exhaust heat recovery.
The Health and Science Center at the Vancouver Island University is currently under construction. It is a 4-storey, 70,000 sf building with a mix of lecture halls, faculty offices, teaching nursing stations and undergraduate chemistry labs. The chemistry labs occupies approximately 20% of the building area and has 24 fume hoods. By incorporating low energy design such as natural ventilation in the lecture and faculty areas, air transfer from the non-lab area to the lab area, and water source heat pumps to recover waste heat for building heating, the building is able to achieve a low modeled energy use of 63 kBtu/sf/year without recovering heat from the fume hood exhaust.
- Understand the requirements and challenges of maintaining fume hood and hazardous exhaust heat recovery system.
- Understand the importance of communication between the designer, owner, facility operator and health and safety department to identify the best energy saving strategies.
- Identify the steps to determine when fume hood exhaust heat recovery is worthwhile
- Strategize energy saving measures based on the building's unique mix of occupancy
Mary is a project manager in Integral Group's Vancouver office with over 15 years of experience in HVAC design and construction. Mary has a strong focus on lab projects including chemistry, foresnics, and biosafety containment labs, and was the lead mechanical engineer for the Quantum Matter Institute Project at the University of British Columbia. Mary is a Registered Professional Engineer in British Columbia, Canada, and a certified Passive House Designer.
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